Sioux valve grinding attachment

[kkkcj]

 

[kkkcj]

I don't know what this is or how it could be used but it was in a Sioux valve seat grinding set.

 

[RTM]

By valve seats, I am not thinking car, but plumbing

 

[rsanter]

What are the numbers on the items

 

[txvwnut]

I believe that is for grinding rocker arms as Sioux had an attachment for that.